Pionodema bellula

Classification
Phylum: Brachiopoda
Class: Rhynchonellata
Order: Orthida
Family: Draboviidae
Genus: Pionodema
Species: Pionodema bellula (Meek, 1873)

Taxonomic Details

History

  • 1873 Orthis bellula James in Meek, Descriptions of Invertebrate Fossils of the Silurian and Devonian Systems: Report of the Geological Survey of Ohio, v. 1, pt. II, p. 1-243, pls. 1-23

Stratigraphic Occurrences

P.bellula_strat

Geographic Occurrences

		
Map point data provided by iDigBio.

Stratigraphic Description

Sequences (Formations)

  • C2 Sequence (Fairview: Fairmount)

Identification in Hand Sample

  • Fine radiating costae
  • Longitudinally semi-oval shell shape
  • Width almost always greater than the length
  • Dorsal valve less convex than the ventral valve
  • Foramen narrow and triangular

Pionodema bellula from the Fairview Formation of Cleves, Ohio (OUIP 343)

Published Description

Davis (1998):

  • Articulate brachiopod. Brachial valve (convex), note fine costae. Fairmount.

Meek (1873):

  • Shell very small, longitudinally semi-oval, or transversely sub-oval, moderately gibbous, sub-equivalve; breadth always greater than the length; hinge line a little less than the greatest breadth of the valves; posterior lateral extremities abruptly rounded, or sub-angular; lateral margins rounding to the front, which is broadly semi-elliptical in outline, or sometimes a little straightened, or even very faintly sinuous at the middle. Interior unknown. Dorsal valve is less convex than the other, with usually a very slight, scarcely perceptible mesial depression near the umbo, that rarely, if ever, extends forward to the middle; beak small, projecting slightly beyond the edge of the area, and merely a little arched; area of comparatively moderate height, flat, or somewhat arched, and inclined more or less obliquely backward and upward; foramen forming a nearly equilateral triangle. Ventral valve most convex near the umbo, and perhaps always showing a very shallow, broad, undefined mesial sinuosity at the front; beak moderately prominent, pointed, inclined backward and a little arched, but not incurved; area comparatively rather high, or from twice to three times the height of that of the other valve, well defined, a little arched, and inclined obliquely backward and downward; foramen narrow-triangular, and extending to the point of the beak. Surface of both valves ornamented by very fine radiating striae, most of which bifurcate two or three times between the beaks and free margins; the lateral ones being moderately arched.